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Objective: To evaluate the accuracy of dental rotational movements using clear aligners with different attachment configurations. Materials and Methods: This retrospective study analysed 212 teeth from 89 patients undergoing Invisalign treatment. Digital models were analysed after the virtual treatment plan (ST1) and after the first treatment phase (ET1) to evaluate the effective clinical rotational movement. The rotational movements of incisors, canines, and bicuspids were measured using data from the Clincheck Movements Table. ST1 and ET1 were compared to determine the actual rotational movement achieved (ST1‐ET1). The presence or absence of attachments (rectangular or optimized) on teeth was analysed. The accuracy of rotational movements among attachment types was compared using the Kruskal‐Wallis test. Multiple linear regressions were conducted with accuracy as the dependent variable and tooth type, gender, and age as predictors. Results: Optimized attachments had the highest median accuracy (70%), followed by rectangular (65%), and without attachment (63%), with no significant differences (p =.5). There were no significant differences across age groups, genders, or tooth types. Baseline accuracy was 68.62% (95% CI: 56.03–81.20, p <.001). Age was a significant predictor (estimate = −0.30, 95% CI: −0.58 – −0.03, p =.032), indicating decreased accuracy with increasing age. The model's R2 was 0.046, with an adjusted R2 of 0.003, indicating minimal variance explained. Conclusion: The addition of attachment configurations to clear aligners improves rotational accuracy, but not significantly. Further advancements in these configurations are needed to enhance the performance of the aligners. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to compare the achieved and predicted root movements in adults after four first‐premolar extractions and Invisalign treatment. Materials and Methods: Thirty‐three consecutive adults (22 Class I, 9 Cusp‐to‐cusp Class II and 2 Cusp‐to‐cusp Class III) from a single clinical division who completed the first series of aligners after premolar extractions were included in this retrospective study. A pretreatment cone‐beam computed tomography model was registered onto the pretreatment surface‐scanned dental model (SSDM) to locate the pretreatment root apices of the whole dentition. These were copied and transferred to the predicted and achieved post‐treatment SSDMs to acquire the locations of the predicted and achieved post‐treatment root apices. The differences between predicted and achieved root movements (DPARMs) were tested using the paired t‐test or Wilcoxon signed rank test. Results: In the anteroposterior direction, posterior root movements of maxillary and mandibular anterior teeth were poorly achieved (3.24–5.74 mm DPARMs, p <.05). In the vertical direction, roots of maxillary anterior teeth achieved greater intrusion (0.70–0.93 mm DPARMs, p <.05), while those of mandibular incisors achieved less intrusion (0.57–0.65 mm DPARMs, p <.05) than predicted. In the mediolateral direction, lateral incisor roots did not move distally (−0.65 to −0.96 mm DPARMs, p <.05), while those of canines did not move buccally, compared with the prediction (−0.75 mm DPARMs, p <.05). Conclusions: In the four first‐premolar extraction treatments with Invisalign, root movements were not achieved as predicted, particularly for anterior teeth in the anteroposterior direction. [ABSTRACT FROM AUTHOR]

Objective: To assess the tooth movement trends during the three stages of maxillary dentition distalization with clear aligners (CA) and to compare the efficacy of different mini‐screw anchorage systems. Materials and Methods: Three‐dimensional (3D) finite element models of three anchorage systems (A, control group; B, buccal mini‐screw anchorage group; C, palatal mini‐screw anchorage group) were established. Three stages of simulating maxillary dentition distalization with CA included maxillary molar distalization (stage 1), maxillary premolar distalization (stage 2) and maxillary anterior teeth retraction (stage 3). Therefore, a total of nine models were constructed to analyse the 3D displacement of maxillary teeth during the distalization process. Results: The displacement pattern of maxillary dentition during distalization was similar across the three groups, but with varying magnitudes. During stage 1, groups B and C exhibited greater amounts of molar distalization compared to group A. Group C also demonstrated the least amount of labial movement of the maxillary central incisor compared to the other two groups. During stage 2, the mesial displacement of the maxillary first molar was less significant in groups B and C than in group A. In the final stage, group C exhibited a greater amount of maxillary anterior retraction compared to groups A and B. Conclusion: The palatal mini‐screw anchorage system was effective in reducing anchorage loss and improving the efficacy of maxillary dentition distalization with CA. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the biomechanical effects of clear aligner (CA) with different shape designs at extraction space (CAES) area during space closing. Materials and Methods: A finite‐element method (FEM) model of mandibular dentition, periodontal ligaments, attachments, and corresponding CA was established. The connecting rod design of CAES was modelled for the control group. Eight test groups with different heights of CAES from −4 mm to +4 mm were designed. Tooth displacement tendencies were calculated. The maximum principal stress in PDLs, teeth, and CAs was analysed. Both global coordinate system and local coordinate system were also used to evaluate individual tooth movements. Results: Across all groups, stresses concentrated on the lingual outer surface of CAESs. For the lowered CAES groups, both the stress value and the stress distribution area at CAESs were increased. The lowered CAES groups showed reduced movement in anterior teeth and less tipping tendency of the canines. Conclusion: The shape of CAES has a biomechanical impact on anterior teeth movement and should be considered in aligner design. The results suggest that increasing the height of CAES can enhance anterior teeth retraction, while lowered CAES may facilitate controlled root movement. Changes in the shape of CAES represent a potential direction for biomechanical improvement of clear aligner in extraction cases and are worth exploring. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this study was to evaluate the therapeutic effect of modified clear Twin Block (CTB) aligner and traditional twin block (TB) appliance from skeletal, dentoalveolar and soft tissue changes in adolescents with skeletal class II malocclusion. Methods: A total of 80 adolescents, included in this study from two medical centres, were distributed into CTB group, TB group and control group based on the treatment they received. Lateral cephalograms at pre‐treatment (T1) and post‐treatment (T2) were measured by modified Pancherz's cephalometric analysis, and dentoskeletal and soft tissue changes were analysed by independent‐sample t‐test, paired‐sample t‐test, ANOVA test and Scheffe's Post Hoc test. Results: Seventy‐five adolescents completed the study, including 32 in the CTB group, 32 in the TB group and 11 in the control group. Both CTB and TB treatment showed significant differences in most dentoskeletal and soft tissue measurements. Compared with the control group, improvements were observed in class II molar relationship through significant different in S Vert/Ms‐S Vert/Mi in the CTB group (P <.01) and the TB group (P <.001), as well as deep overjet through significant different in S Vert/Is‐S Vert/Ii in the CTB group (P <.001) and the TB group (P <.001). Besides, the CTB group also showed less protrusion of lower incisors and resulted in a more significant improvement in profile with fewer adverse effects on speaking, eating and social activities. Conclusions: For adolescents with skeletal class II malocclusion, CTB appliance was as effective as TB on improving dentoskeletal and soft tissue measurements, featuring more reliable teeth control and patient acceptance. [ABSTRACT FROM AUTHOR]

Background and Objectives: Clear aligners‐related posts are popularized on social media platforms to educate patients and peers and to market aligners in dental practices. This study aimed to characterize the account credentials and content of the top‐performing posts to understand the spread of clear aligners‐related information on Instagram. Materials and Methods: This cross‐sectional web‐based study analysed 13 Instagram clear aligners‐related hashtags. Content analysis was performed for the "Top 10 posts" listed under the "Top" section for each hashtag within Instagram, as sorted by Instagram's algorithm. Data were analysed for the poster's background, credentials, role, post format, content, and engagement level ratio. Duplicate posts and those not relevant to clear aligners were excluded. Quantitative and qualitative analyses of the collected data were conducted. Results: A total of 29 192 596 posts mentioned the selected hashtags, of which 130 posts were screened in this study. Most posts were authored by dentists (n = 84), 79.8% of them were orthodontic specialists. Self‐promotional posts comprised 90.2%, while educational posts accounted for only 8.9%. Interestingly, the number of likes and comments received on posts by patients (n = 19, median = 112, IQR = 340) was significantly higher than those posted by dentists (n = 84, median = 93, IQR = 81.75) (P =.004). Conclusion: More than 29 million posts about clear aligners were identified on Instagram. Orthodontists are the leading authors of aligners hashtags. However, the majority of the posts are self‐promotional and have nonfactual information. Social media awareness among orthodontic specialists may help provide more evidence‐based content about clear aligners and can act as an interactive networking and health communication platform. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to assess the loss rate of attachments and investigate its probable influencing factors in patients during orthodontic therapy with clear aligners. Materials and Methods: A total of 55 patients treated with clear aligners were enrolled in this prospective clinical study. The loss rate of attachments was evaluated after a 6‐month follow‐up since the initial bonding was finished. The attachment survival curves were gone through Kaplan–Meier estimates. The Cox regression model with shared frailty was conducted to evaluate the hazard ratios (HRs) for the following factors, including sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount, arch, tooth position and attachment type. Results: There were a total of 47 patients (14 males and 33 females; and mean age: 26.77 ± 8.45) in which 722 attachments were involved in the final analysis. During the 6‐month follow‐up, 99 attachments were lost by 40 participants. The overall loss rate was 13.7%. The loss of attachments was more common in the early months of therapy. During the first 2 months, 71 attachments were lost. The loss rate of attachments was not significantly affected by sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount and attachment type (P > 0.05). The loss rate of mandibular attachments was 1.8 times that of maxillary attachments (HR = 1.8; 95% CI: 1.2–2.8; P = 0.009). The loss rate of molar attachments was 5.5 times that of incisor attachments (HR = 5.5; 95% CI: 1.6–19; P = 0.007). Conclusion: During the first 6 months, the overall loss rate of attachments was 13.7%. In the early months of therapy, loss of attachments was more common. The loss rate decreased as treatment time increased. Loss of attachments was significantly affected by arch and tooth position, with higher loss rates in the mandibular arch and molars. Besides, loss of attachments was not affected by sex, age, dental malocclusion, vertical skeletal pattern, anterior overbite, operators, tooth extraction, attachment amount and attachment type. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study is to evaluate the bond strengths of two different composite types used in the production of clear aligner attachments on monolithic zirconia with three different surface roughening processes. Materials and Methods: Packable composite Filtek Z250 was used in one group (PC‐G) and flowable composite Filtek Supreme Ultra Flowable was used in the other group (FC‐G). PC‐G and FC‐G groups were also divided into three subgroups as diamond bur+silane (Group 1), 50 μm aluminium oxide (Al2O3) sandblasting+silane (Group 2) and 110 μm Al2O3 sandblasting+silane (Group 3). Scanning electron microscopy (SEM) analysis was performed. Clear aligner attachments were bonded to the monolithic zirconia specimens. Shear bond strength (SBS) values were measured. Statistical analysis was performed using two‐way ANOVA and post‐hoc Tukey's tests (P <.05). Results: The highest SBS value was found in PC‐G sandblasted with 110 μm Al2O3 (P ≤.001). The etching method with 110 μm sandblasting showed high SBS values in both composite types. The lowest SBS value gave FC‐G in diamond bur roughening (P ≤.001). Conclusions: For the bonding of clear aligner attachments on monolithic zirconia, roughening with 110 μm particle size sandblasting and the choice of packable composite could be recommended in terms of retention. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the subgingival microbiological changes during the first six months of therapy with clear aligners (CAs) and fixed appliances (FAs). The null hypothesis was that there would be no microbiological differences between the two. Setting/Sample: Two groups of patients to be treated, respectively, with CAs (14 patients; 9 females and 5 males; mean age 21 years ± 0.25) and FAs (13 patients; 8 females and 5 males; mean 14 years ± 0.75) were consecutively recruited. Materials and Methods: Subgingival microbiological samples were obtained at the right upper central incisor and right first molar at four different time points: before appliance fitting (T0), and at 1 month (T1), 3 months (T3) and 6 months (T6) thereafter. Total bacterial load (TBL) and counts of the bacteria Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Fusobacterium nucleatum, Campylobacter rectus, Treponema denticola and Tannerella forsythia were determined using real‐time PCR. Results: Total bacterial load did not vary in the CA group, while a significant increase was detected after 3 and 6 months of treatment in the FA group. Unlike red complex species, C rectus and F nucleatum were often detected: levels remained stable in the CA group but increased progressively in the FA group. Conclusion: The type of orthodontic appliance influences the subgingival microbiota. TBL increased in the FA group but not in the CA group, although the levels of the individual periodontal pathogenic bacteria species did not significantly increase during the observation period. [ABSTRACT FROM AUTHOR]

Objective: To analyse through a systematic review the effectiveness of clear aligners by assessing: (a) predictability of clear aligners and (b) treatment outcome comparison of clear aligner therapy with fixed appliance therapy.Methods: An electronic search was made from January 2014 to April 2019 using MEDLINE, Embase, Web of Science and LILACS databases without any limitations on language. Three reviewers independently assessed the articles. Quality assessment of observational studies and randomized control trial was done by using the ROBINS tool and Cochrane risk of bias tool, respectively. GRADE instrument was used to assess certainty level for each identified outcome.Results: Seven eligible articles (one randomized controlled trial and six retrospective cohort) were included in our systematic review. Most of the studies (six out of seven) had a moderate risk of bias and one had a high risk of bias.Conclusions: 'Low to moderate level' of certainty in regard to specific clear aligner therapy tooth movements' efficiency was identified. Clear aligners may produce clinically acceptable outcomes that could be comparable to fixed appliance therapy for buccolingual inclination of upper and lower incisors in mild to moderate malocclusions. However, not all potential clinical scenarios have been assessed in the included studies. Most of the tooth movements may not be predictable enough to be accomplished with only one set of trays with clear aligners despite the recent advances in technology. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the external root resorption in participants receiving clear aligners and compare it with those treated with fixed appliances. Systematic review with meta-analysis. Electronic and manual search were performed, and specific inclusion and exclusion criteria were used. Data extraction and analysis were conducted by two investigators independently. The original outcome underwent statistical pooling by Review Manager 5. The quality of studies was assessed by ROBINS-I tool. A total of 11 studies were included for qualitative analysis (six in moderate risk of bias while another five in serious risk of bias), and three of them were statistically pooled in meta-analysis. The external root resorption in treatment with clear aligners was significantly lower than that with fixed appliances (SMD = -0.65, 95% CI [-0.74, -0.55], P < .01). Subgroup analysis on each quadrant of incisors was consistent with the former result. Current evidences suggest that clear aligners might not avoid root resorption, but the incidence and severity of resorption could both be lower compared with results reported by treatment with fixed appliances. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to perform a systematic review of the orthodontic literature with regard to efficiency, effectiveness and stability of treatment outcome with clear aligners compared with treatment with conventional brackets.Methods: An electronic search without time or language restrictions was undertaken in October 2014 in the following electronic databases: Google Scholar, the Cochrane Oral Health Group's Trials Register, Scopus, CENTRAL, MEDLINE via OVID, EMBASE via OVID and Web of Science. We also searched the reference lists of relevant articles. Quality assessment of the included articles was performed. Two authors were responsible for study selection, validity assessment and data extraction.Results: Four controlled clinical trials including a total of 252 participants satisfied the inclusion criteria. We grouped the trials into four main comparisons. One randomized controlled trial was classified as level 1B evidence, and three cohort studies were classified as level 2B evidence. Clear aligners appear to have a significant advantage with regard to chair time and treatment duration in mild-to-moderate cases based on several cross-sectional studies. No other differences in stability and occlusal characteristics after treatment were found between the two systems.Conclusions: Despite claims about the effectiveness of clear aligners, evidence is generally lacking. Shortened treatment duration and chair time in mild-to-moderate cases appear to be the only significant effectiveness of clear aligners over conventional systems that are supported by the current evidence. [ABSTRACT FROM AUTHOR]